Industrial robots often operate in an environment where the robot unintentionally might come into contact with other object such as humans working in the local, other robots, other tooling machines or objects on which work is performed. This implies a risk that the robot itself or the object with which it collides might be damaged or a person might be injured. A large part of these risks can be avoided by logistic measures, however not always to 100%. It is therefore a need to provide some kind of protection on those parts of the robot for which there is a collision risk, in particular elbows and the like where there are joints between arms of the robot. It is thus known to apply an impact absorbing structure surrounding such robot parts. It is also known to provide robot parts with a protective cover in order to protect components related to the robot from being affected by contamination of the atmosphere around the robot, e.g. protecting cables from being affected by paint mist or the like.
Examples of protection structures protecting against impacts and/or contamination can be found in U.S. Pat. No. 5,732,599, EP 0988939, JP 5023992, US 20050103147 and U.S. Pat. No. 7,069,664.
To achieve that an industrial robot that operates alongside human workers is intrinsically safe structural parts of the robot is encased in an impact absorbing material.
A further requirement in terms of safety is that cabling in the robot arm has to be concealed in order to prevent accidents by entanglement. In arrangements where hollow-shaft drive trains are not employed, the pressure of padding on the outside of the robot structure conflicts with free movement of the cables. The conflict may be resolved by introducing a volume of free space in which the cable can move between the rotating joint components and the padding. However, this enlarges the outer dimensions of the arm thereby compromising its working range.
There might also be other reasons that lead to a requirement of a free space between the robot part and the surrounding protective padding.